Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual era a taxa para adultos quando a taxa para jovens de 16-17 anos era de £3.40?
 ###Tabelas: CREATE TABLE current_and_past_rates (current_and_past_rates_id AUTO_INCREMENT PRIMARY KEY, From VARCHAR, Adult Rate VARCHAR, Development Rate VARCHAR, 16-17 Year Olds Rate VARCHAR, Apprentice Rate VARCHAR) CREATE TABLE seasons_summary (seasons_summary_id AUTO_INCREMENT PRIMARY KEY, Season INT, Champion VARCHAR, Runner-up VARCHAR, Third Place VARCHAR, Top scorer VARCHAR, Best Player VARCHAR) CREATE TABLE top_scorers_in_loi (top_scorers_in_loi_id AUTO_INCREMENT PRIMARY KEY, Ranking INT, Nationality VARCHAR, Name VARCHAR, Years VARCHAR, Goals INT) CREATE TABLE planitia (planitia_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Latitude VARCHAR, Longitude VARCHAR, Diameter (km) INT, Year named INT) CREATE TABLE module_specifications (module_specifications_id AUTO_INCREMENT PRIMARY KEY, Designation VARCHAR, Bus width (bits) INT, Channels VARCHAR, Clock rate (MHz) INT, Bandwidth (MB/s) INT)  
SELECT Adult Rate FROM current_and_past_rates WHERE 16-17 Year Olds Rate = £3.40